Table 1. CPs of protozoan parasites.
| Protozoan parasite | Enzymes | EuPathDB entry | Proposed function | Reference |
|---|---|---|---|---|
| Entamoeba histolytica | EhCP1 | EHI_074180 | Invasion, virulence factors, induces macrophage proinflammatory response, tight junction proteolysis, degradation of ECM (fibronectin, laminin, collagen) | [8, 10, 16, 18] |
| EhCP2 | EHI_033710 | Invasion, virulence factors, induces macrophage proinflammatory response, tight junction proteolysis, degradation of ECM (fibronectin, laminin, collagen) | [6–8, 10, 16, 18] | |
| EhCP5 | EHI_168240 | Invasion, virulence factors, induces macrophage proinflammatory response, degradation of ECM (fibronectin, laminin, collagen), degradation of IgA, IgG, pro–IL-1β, pro–and mature IL-18 (immunoevasion), inactivation of anaphylatoxins | [10–15] | |
| EhCP7 | EHI_039610 | Invasion, virulence factors, induces macrophage proinflammatory response | [16, 18] | |
| EhCP (unspecified) | unspecified | Virulence factor, host defense evasion | [6–8] | |
| EhCP (unspecified) | unspecified | Parasite encystation–excystation | [17] | |
| Leishmania sp. | CPA, CPB1, CPB2 | LmxM.19.1420, LmjF.19.1420, LinJ.19.1460; LmxM.07.0550, LmjF.08.1010; | Virulence factor; immunomodulators; parasite metabolism modulator | [26, 33, 35, 37, 149] |
| CPC | LmxM.08_29.0820, LmjF.29.0820, LinJ.29.0860 | In vitro virulence factor; role in parasite cell death | [42] | |
| Atg4 | LmjF.30.0270, LinJ.30.0270 | Autophagy (differentiation and virulence) | [41, 150] | |
| otubain | LmxM.17.1400, LmjF.17.1400, LinJ.17.1520 | Deubiquitination, proinflammatory activity | [42] | |
| Trypanosoma brucei | TbCatL (brucipain, rhodesain) | Tb927.6.960-Tb927.6.1060 | CatL-like activity, virulence factor, promotes crossing of the BBB, host immune evasion | [51, 54, 151] |
| TbCatB | Tb427.06.560 | Virulence factor, iron acquisition | [59–61, 152] | |
| T. cruzi | Cruzain (GP57/51, TcCatL) | TCDM_05847-t26_1 | Virulence factor, evasion of immune system, invasion of host cells, parasite differentiation | [2, 3, 73] |
| Calpain-like (TcCatB) | TcCLB.506227.130, TCDM_01392 | Signaling transduction, metacyclogenesis | [75] | |
| Atg4 | TCDM_05817-t26_1, TCDM_06287-t26_1 | Parasitic autophagy important in differentiation and virulence | [76, 153] | |
| Cryptosporidium sp. | Cryptopain (CatL-like, CpaCATL-1) | cubi_02618-t31_1, cgd3_680, cgd4_2110, cgd6_4880, cgd7_2850 | Host cell invasion | [89, 90] |
| CpOTU (otubain) | cgd6_2750 | Ubiquitin pathway; peak in the oocyst stage | [93] | |
| Plasmodium sp. | Falcipain-1 | PF3D7_1458000.1 | Oocyst production | [110] |
| SERA family. Atypical CP and dipeptidyl aminopeptidase 3. | PF3D7_0207500 | Invasion of hepatocytes by sporozoites | [103, 106] | |
| Falcipain-2, falcipain-3, dipeptidyl aminopeptidase 1 | PF3D7_1115700.1, PF3D7_1115400.1 | Hemoglobin hydrolysis | [101, 122] | |
| PfOTU | PF3D7_1031400 | Apicoplast development and homeostasis | [115] | |
| Toxoplasma sp. | Single copy gene CatB (TgCPB) | TGME49_249670 | Cell invasion and replication | [140, 142] |
| Single copy gene CatL (TgCPL) | TGME49_321530 | Host cell invasion, digestion of cytosolic proteins | [134, 141] | |
| TgCP1 and TgCP2 (CatC-like), exopeptidases | TGME49_289620, TGME49_276130 |
Expressed in tachyzoites, degrade peptides | [137] |
Abbreviations: BBB, blood–brain barrier; CP, cysteine proteases; ECM, extracellular matrix; EuPathDB, Eukaryotic Pathogen Database; sp., species.